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LING 388: Language and Computers

LING 388: Language and Computers. Sandiway Fong Lecture 15 10/13. Administrivia. Reminder Homework 5 due next Monday. Today’s Topic. case study How to implement the passive construction in a traditional grammar framework verb inflection constraints between auxiliary and main verbs

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LING 388: Language and Computers

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  1. LING 388: Language and Computers Sandiway Fong Lecture 15 10/13

  2. Administrivia • Reminder • Homework 5 due next Monday

  3. Today’s Topic • case study • How to implement the passive construction in a traditional grammar framework • verb inflection • constraints between auxiliary and main verbs • subcategorization and adjuncts

  4. Example Grammar • grammar so far • including extra arguments for parse tree • and simple determiner-noun agreement • s(s(Y,Z)) --> np(Y), vp(Z). • np(np(Y)) --> pronoun(Y). • np(np(D,N)) --> det(D,Number), common_noun(N,Number). • det(det(the),_) --> [the]. • det(det(a),sg) --> [a]. • common_noun(n(ball),sg) --> [ball]. • common_noun(n(man),sg) --> [man]. • common_noun(n(men),pl) --> [men]. • pronoun(i) --> [i]. • pronoun(we) --> [we]. • vp(vp(Y)) --> unergative(Y). • vp(vp(Y,Z)) --> transitive(Y), np(Z). • unergative(v(ran)) --> [ran]. • transitive(v(hit)) --> [hit]. • query • ?- s(X,Sentence,[]). Sentence = Prolog list of words all rules take one extra argument for the parse tree however det and common_noun take two extra arguments: one for the parse tree and one for Number verb classes only one extra argument for the parse tree

  5. in English... passivization applies only to transitive verbs I hit the ball (active) the ball was hit (passive) transitive(v(hit)) --> [hit]. i.e. passivization should only apply to verbs encoded in the grammar using the transitive non-terminal not for unaccusative or unergative verbs I arrived *I was arrived unaccusative(v(arrived)) --> [arrived]. We ran *We were ran/run unergative(v(ran)) --> [ran]. Passivization

  6. s np vp s v np i det n vp hit np ball the aux v det n ball the was hit Passivization • simple phrase structure • I hit the ball (active) • the ball was hit (passive) A first pass (simplistic non-movement account) • avoiding empty categories for simplicity (can be added, see later slide): • the ball was hit e • [the ball]i was hit ti

  7. s vp np aux v det n ball the was hit Passivization • phrase structure • the ball was hit (passive) • rules (active sentence) • s(s(Y,Z)) --> np(Y), vp(Z). • vp(vp(Y,Z)) --> transitive(Y), np(Z). • transitive(v(hit)) --> [hit]. • new rules (passive sentence) • vp(vp(A,V)) --> aux(A), transitive(V). • aux(aux(was)) --> [was].

  8. Passivization • query • ?- s(X,[the,ball,was,hit],[]). • computation tree • ?- s(X,[the,ball,was,hit],[]). • ?- np(Y,[the,ball,was,hit],L). • ?- vp(Z,L,[]). • ?- np(Y,[the,ball,was,hit],L). • Y=np(det(the),n(ball)) L=[was,hit] • ?- vp(vp(A,V),[was,hit],[]). • ?- aux(A,[was,hit],L’). • ?- transitive(V,L’,[]). • ?- aux(A,[was,hit],L’). • A=aux(was) L’=[hit] • ?- transitive(V,[hit],[]). • V=v(hit) • X=s(np(det(the),n(ball)),vp(aux(was),v(hit))) s(s(Y,Z)) --> np(Y), vp(Z). np(np(Y)) --> pronoun(Y). np(np(D,N)) --> det(D,Number), common_noun(N,Number). det(det(the),_) --> [the]. det(det(a),sg) --> [a]. common_noun(n(ball),sg) --> [ball]. common_noun(n(man),sg) --> [man]. common_noun(n(men),pl) --> [men]. pronoun(i) --> [i]. pronoun(we) --> [we]. vp(vp(A,V)) --> aux(A), transitive(V). vp(vp(Y)) --> unergative(Y). vp(vp(Y,Z)) --> transitive(Y), np(Z). unergative(v(ran)) --> [ran]. transitive(v(hit)) --> [hit]. aux(aux(was)) --> [was].

  9. Passivization • We are (free to) modify the parse for the VP constituent to include items not found in the input • sometimes this can be very useful • e.g. there are good linguistic reasons why we might prefer to write • vp(vp(Aux,vp(V,np(trace))),Number) --> aux(Aux,Number), transitive(V,Ending), {Ending = en}. instead, which produces: s vp np vp aux det n v np ball the was hit trace

  10. Passive Morphology other morphological rules (progressive) be V-ing e.g. was eating (passive+progressive) e.g. was being eaten • verbal inflection • hit eat • hits eats (-s) • hit ate (-ed) • hit eaten (-en) • verbal inflection and passive morphology • rule: (passive) be V-en • was hit (ambiguous between -ed and -en) • *was ate (-ed) • was eaten (-en) • how to implement this restriction? • vp(vp(A,V)) --> aux(A), transitive(V). • idea • use an extra argument to indicate the verb form fortransitive

  11. Passive Morphology • verbal inflection • eat (root) • eats (-s) • ate (-ed) • eaten (-en) • use an extra argument to signal the inflected form, e.g. • transitive(v(eat),root) --> [eat]. • transitive(v(eat-s),s) --> [eats]. • transitive(v(eat-ing),ing) --> [eating]. • transitive(v(eat-ed),ed) --> [ate]. • transitive(v(eat-en),en) --> [eaten]. • original rule • vp(vp(A,V)) --> aux(A), transitive(V). • modified rule • vp(vp(A,V)) --> aux(A), transitive(V,en). equivalently vp(vp(A,V)) --> aux(A), transitive(V,Ending),{Ending=en}. Constraint for -en realized by Prolog pattern-matching

  12. Passive Morphology • grammar rules (partial) • transitive(v(eat),root) --> [eat]. • transitive(v(eats),s) --> [eats]. • transitive(v(ate),ed) --> [ate]. • transitive(v(eaten),en) --> [eaten]. • vp(vp(A,V)) --> aux(A), transitive(V,en). • aux(aux(was)) --> [was]. • query • ?- vp(X,[was,eaten],[]). • computation tree • ?- vp(X,[was,eaten],[]). X=vp(A,V) • ?- aux(A,[was,eaten],L). • ?- transitive(V,en,L,[]). • ?- aux(A,[was,eaten],L). • A=aux(was) L=[eaten] • ?- transitive(V,en,[eaten],[]). • V=v(eaten) example: was eaten

  13. attempted match fails Passive Morphology • grammar rules (partial) • transitive(v(eat),root) --> [eat]. • transitive(v(eats),s) --> [eats]. • transitive(v(ate),ed) --> [ate]. • transitive(v(eaten),en) --> [eaten]. • vp(vp(A,V)) --> aux(A), transitive(V,en). • aux(aux(was)) --> [was]. • query • ?- vp(X,[was,ate],[]). • computation tree • ?- vp(X,[was,ate],[]). X=vp(A,V) • ?- aux(A,[was,ate],L). • ?- transitive(V,en,L,[]). • ?- aux(A,[was,ate],L). • A=aux(was) L=[ate] • ?-transitive(V,en,[ate],[]). • No example: *was ate

  14. s s vp np np vp aux v det n det n vp pp ball the was hit ball the aux v p np was hit by me Subject in By-Phrase • phrase structure • I hit the ball (active) • the ball was hit (passive) • the ball was hit by me (passive + subject in by-phrase) optional prepositional phrase (PP) is adjoined to the verb phrase (VP)

  15. s np vp det n vp pp ball the aux v p np was hit by me Subject in By-Phrase • phrase structure • I hit the ball (active) • the ball was hit (passive) • the ball was hit by me (passive + subject in by-phrase) • add PP rules • pp(pp(P,NP)) --> preposition(P), np(NP). • preposition(p(by)) --> [by]. • add VP adjunction rule • vp(vp(VP,PP)) --> vp(VP), pp(PP). • add pronoun rule • np(np(Y)) --> pronoun(Y). • pronoun(i) --> [i]. • pronoun(we) --> [we]. • pronoun(me) --> [me]. • there is a Case Constraint • (not implemented here) • by me • *by I • *me hit the ball

  16. s vp np aux v det n ball balls the was were hit Other Constraints • examples • I hit the ball (active) • the ball was hit (passive) • the ball was hit by me (passive + by-phrase) • *the ball were hit by me • *the balls was hit by me • the balls were hit by me • Subject-Verb Agreement Rule • subject must agree with the verb for number • np(np(D,N)) --> det(D,Number), common_noun(N,Number). • common_noun(n(ball),sg) --> [ball]. • common_noun(n(balls),pl) --> [balls]. • np(np(D,N),Number) --> det(D,Number), common_noun(N,Number).

  17. s number vp np number number number aux v det n ball balls the was were hit Other Constraints • examples • the ball was hit by me (passive + by-phrase) • *the ball were hit by me • *the balls was hit by me • the balls were hit by me • Subject-Verb Agreement Rule • subject must agree with the verb for number • must propagate number feature up the tree! • np(np(D,N),Number) --> det(D,Number),common_noun(N,Number). • common_noun(n(ball),sg) --> [ball]. • common_noun(n(balls),pl) --> [balls]. • s(s(Y,Z)) --> np(Y,Number), vp(Z). number • s(s(Y,Z)) --> np(Y,Number), vp(Z,Number).

  18. Grammar so far • new additions today • verbal inflection and passive morphology • (passive) be V-en • PP by-phrase • “by me” • Subject-Verb Agreement Rule • “the ball/balls was/were” • grammar is still not fully implemented • see underscores “-” for Subject-Verb Agreement s(s(Y,Z)) --> np(Y,Number), vp(Z,Number). np(np(Y),_) --> pronoun(Y). np(np(D,N),Number) --> det(D,Number), common_noun(N,Number). det(det(the),_) --> [the]. det(det(a),sg) --> [a]. common_noun(n(ball),sg) --> [ball]. common_noun(n(balls),pl) --> [balls]. common_noun(n(man),sg) --> [man]. common_noun(n(men),pl) --> [men]. pronoun(i) --> [i]. pronoun(we) --> [we]. pronoun(me) --> [me]. pp(pp(P,NP)) --> preposition(P), np(NP,_). preposition(p(by)) --> [by]. vp(vp(VP,PP),_) --> vp(VP,_), pp(PP). vp(vp(A,V),Number) --> aux(A,Number), transitive(V,en). vp(vp(Y),_) --> unergative(Y). vp(vp(Y,Z),_) --> transitive(Y,_), np(Z,_). unergative(v(ran)) --> [ran]. transitive(v(hit),_) --> [hit]. transitive(v(eat),root) --> [eat]. transitive(v(eats),s) --> [eats]. transitive(v(ate),ed) --> [ate]. transitive(v(eaten),en) --> [eaten]. aux(aux(was),sg) --> [was]. aux(aux(were),pl) --> [were].

  19. Grammar built in class: Part 1 • s(s(Y,Z)) --> np(Y,Num1), vp(Z,Num2), {Num1 = Num2}. % Partial Subject-Verb agreement • np(np(Y),Number) --> pronoun(Y,Number). • np(np(D,N),Number) --> det(D,Number), common_noun(N,Number). • det(det(the),_) --> [the]. • det(det(a),sg) --> [a]. • common_noun(n(apple),sg) --> [apple]. • common_noun(n(ball),sg) --> [ball]. • common_noun(n(man),sg) --> [man]. • common_noun(n(men),pl) --> [men]. • pronoun(i,sg) --> [i]. • pronoun(we,pl) --> [we]. • pronoun(me,sg) --> [me]. • vp(vp(Y),_) --> unergative(Y). • vp(vp(Y,Z),_) --> transitive(Y,_), np(Z,_). • vp(vp(Aux,vp(V,np(trace))),Number) --> aux(Aux,Number), transitive(V,Ending), {Ending = en}. • vp(vp(VP,NP),Number) --> vp(VP,Number), pp(NP).

  20. Grammar built in class: Part 2 • unergative(v(ran)) --> [ran]. • transitive(v(hit),root) --> [hit]. • transitive(v(hit-s),s) --> [hits]. • transitive(v(hit-ing),ing) --> [hitting]. • transitive(v(hit-ed),ed) --> [hit]. • transitive(v(hit-en),en) --> [hit]. • transitive(v(eat),root) --> [eat]. • transitive(v(eat-ing),ing) --> [eating]. • transitive(v(eat-s),s) --> [eats]. • transitive(v(eat-ed),ed) --> [ate]. • transitive(v(eat-en),en) --> [eaten]. • aux(aux(was),sg) --> [was]. • aux(aux(was),pl) --> [were]. • pp(pp(P,NP)) --> p(P), np(NP,_). • p(p(by)) --> [by].

  21. Outstanding issues • The relative order of the VP rules is critical e.g. what happens when the rule vp(vp(VP,PP),Number) --> vp(VP,Number), pp(PP). is moved around in the program for the following query? ?-s(X,[the,balls,were,hit,by,me],[]). • how to block recursion (iteration) for *the balls were hit by me by the man? ?- s(X,[the,balls,were,hit,by,me,by,the,man],[]). • would (less linguistically desirable) ternary branching for the VP adjunct work better computationally? e.g. vp(vp(A,V,PP)) --> aux(A), transitive(V,en), pp(PP).

  22. More to come… • Grammar also has infinite loops, i.e. does not terminate properly • We’ll fix these issues next time

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